Bill-Harrison-Lesson 7-Aug2010 – Minor Keys (Click above to download the accompanying pdf file for musical examples)
Correct me if I’m wrong about this, but it seems that the subject of “minor” gets short shrift in lessons and discussions about jazz harmony. Perhaps this is because the major scale and its modes take a lot of time to learn and use with ease. Maybe it’s because major scale harmonies (I, vi, ii and V) are so common in standard tunes and the mainstream jazz repertoire. But I think that one of the main avoidance factors is that there are so many kinds of minor scales that many musicians find the whole subject terribly confusing.
I know I did, for many years. So I’m going to do you a favor and (hopefully) de-mystify minor in one short lesson.
When we say that a song (or a section of it) is in a minor key we mean that this chunk of music is written using material from the major scale that shares its key signature. This is the origin of the term “relative minor”. Recall that the natural minor scale (also called aeolian mode) is just the major scale starting on the 6th degree. (Ex. 1) It is your “go to” choice for the chord that is built on the same degree – our old friend vi-7.
Now here’s the allegedly tricky part: Natural minor has an inherent weakness if we want to use it as our home (or tonic) scale. The problem is that this scale has no leading tone (also known as the major 7th). Instead, there is a wimpy sounding whole step from the minor 7th up to the root (or 8). (Ex. 1) What this means is that there is no functional V7 – I present in the natural minor scale. Without that harmonic formula our ability to create tension and release is severely curtailed.
Recall that V7 – I is the most common of all cadences in western music. All of the familiar aspects of the functional harmony we know and love and use every day would be non-existent without V7 resolving to I. The V7 – I cadence depends upon the movement (or resolution) of two notes: the 7th degree of the scale moving up to the root and the 4th descending to the 3rd. (Ex. 2) shows how this works in major keys.
The sad fact is that we can’t construct a dominant 7th chord on the V in natural minor because the 3rd of that chord is minor. So there can be no V7 – I cadence if we use this scale as our home base. What is a composer or improvisor to do if we can’t rely on the strong pull of V going to I? (Ex. 3)
Fortunately this problem was solved several centuries ago by some wily folks who manufactured a new scale by simply raising the 7th up a half step. You most likely already know this one: the harmonic minor. That unique minor 6th / major 7th combination is the result of the need for a leading tone (and therefore a major 3rd on the V chord).
So when we say “minor key” we really mean the harmonic minor scale built on the 6th degree of the relative major key. Functionally speaking, the relative minor for the key of C major is A harmonic minor. We create harmonic minor by raising the 7th degree of natural minor one half step.
There’s really no mystery to it at all!
I have to include a caveat for the harmony mavens: the harmonic minor is NOT the only scale that is used to signify “i” in minor. We’ll discuss the intricacies of the melodic minor scale another day.
And next time we’ll apply this theory to our role as bass line creators.